Two IC TDA2003 are used here, which are connected to oscillators and their results are identical, but 180 out of phase. Capacitors C3 and C6 determine the frequency of these oscillators respectively. When IC1's output charges capacitor C1 to the voltage across diode D2. When the output of IC1 is high, this voltage is also added to the C1. Now the output of IC2 is low, the diode D1 is forward biased and the capacitor C2 is charged by the voltage across C1.

A voltage limiter circuit in series with transistors and a zener diode is added to the output stage in order to avoid overshoot of the output voltage. With the present configuration, the theoretical output voltage will be around 14 volts. Capacitor C8 is the output filter and capacitor C5 is the input filter.